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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').

2445 results found.

  1. IceCube-200421A - IceCube observation of a high-energy neutrino candidate event
  2. GRB 200415A: MASTER imspection and possible localisation
  3. GRB 200415A: Fermi GBM observation
  4. IPN triangulation of GRB 200415A (possible Magnetar Giant Flare in Sculptor Galaxy?)
  5. GRB 200405B: Further Swift-XRT observations
  6. IceCube-200410A: Possible associated excess in INTEGRAL SPI-ACS prompt observation
  7. IceCube-200410A - IceCube observation of a high-energy neutrino candidate event
  8. GRB 200410A: Swift detection of a burst with a possible optical counterpart
  9. GRB 200405B: Swift-XRT observations
  10. GRB 200405B: Swift/BAT-GUANO detection and *possible* arcminute localization of a short GRB
  11. Chandra observations of GW170817 at 2.5 years since merger (All epochs 4 of 4)
  12. LIGO/Virgo S200316bj: No counterpart candidates in Fermi-LAT observations
  13. LIGO/Virgo S200311bg: No significant counterpart candidates in Fermi-LAT observations
  14. Chandra observations of GW170817 ~ 2.5 years since merger (epoch 1 of 4)
  15. LIGO/Virgo S200302c: No significant counterpart candidates in Fermi-LAT observations
  16. GRB 200228B: Mondy, TSHAO, AbAO and CrAO optical observations, afterglow candidate
  17. GRB 200228B: Liverpool Telescope imaging
  18. IceCube-200227A: IceCube observation of a high-energy neutrino candidate event
  19. LIGO/Virgo S200225q: No counterpart candidates in Fermi-LAT observations
  20. LIGO/Virgo S200224ca: No counterpart candidates in Fermi-LAT observations
  21. GRB 200219С: Mondy and TSHAO optical observations
  22. GRB 200219C: Nanshan/NEXT optical upper limit and possible host galaxy from PanSTARRS
  23. LIGO/Virgo S200219ac: No counterpart candidates in Fermi-LAT observations
  24. GRB 200216B: second epoch optical upper limit at Mondy observatory
  25. GRB 200219A: MASTER catalog automatic possible Host Galaxy candidate
  26. GRB 200216B: Mondy and AbAO optical upper limits
  27. GRB 200216B - possible IR counterpart from VLT
  28. GRB 200216B: Nanshan/NEXT early optical upper limit and possible host galaxy
  29. GRB 200216B: Swift detection of a burst
  30. LIGO/Virgo S200213t: Possible host galaxies in the bilby skymap
  31. GRB 200215A Possible host galaxy in PanSTARRS
  32. LIGO/Virgo S200213t: MASTER possible Kilonova candidate in PGC315337
  33. LIGO/Virgo S200114f: Gemini Spectra of AT 2020vu, AT 2020vw, AT 2020vy, and AT 2020vz
  34. LIGO/Virgo S200213t: More Candidates from the Zwicky Transient Facility
  35. LIGO/Virgo S200213t: No counterpart candidates in Fermi-LAT observations
  36. LIGO/Virgo S200213t: Neutrino and galaxies cross-match
  37. LIGO/Virgo trigger S200213t: Possible host galaxies
  38. LIGO/Virgo S200208q: No counterpart candidates in Fermi-LAT observations
  39. GRB 200205A = Swift J0840.7-3516, A newly discovered transient X-ray Pulsar
  40. GRB 200205A: Swift detection of a burst with a possible UV counterpart
  41. AMON IceCube-HAWC_200202A: MASTER optical inspect
  42. LIGO/Virgo S200129m: No counterpart candidates in Fermi-LAT observations
  43. LIGO/Virgo S200128d: No counterpart candidates in Fermi-LAT observations
  44. Fermi-LAT ANTARES 200127.79 coincidence: MASTER alert observation and presence of young pulsar close to error-box
  45. IceCube-200120A: IceCube observation of a high-energy neutrino candidate event
  46. LIGO/Virgo S200114f: SOAR spectroscopy of AT2020zf, AT2020ace and AT2020ach
  47. LIGO/Virgo S200115j: No counterpart detection within possible host galaxies observed by the GRAWITA-Savelli telescope
  48. GRB 200115A: Mondy optical observations and correction to GCN 26790
  49. LIGO/Virgo S200105ae: More candidates from the Zwicky Transient Facility
  50. LIGO/Virgo S200115j: Updated Sky Localization and source properties
  51. LIGO/Virgo S200114f: More candidates from the Zwicky Transient Facility
  52. IceCube-200117A: IceCube observation of a high-energy neutrino candidate event
  53. LIGO/Virgo S200114f: ZTF Forced Photometry of the Swift Source S200114f_X2
  54. LIGO/Virgo S200114f: Possible X-ray transient
  55. LIGO/Virgo S200115j High Rank XRT sources are spurious
  56. LIGO/Virgo S200115j: No counterpart candidates in Fermi-LAT observations
  57. LIGO/Virgo S200115j: Candidates from the Zwicky Transient Facility
  58. LIGO/Virgo S200115j: Revised list of possible host galaxies with the new skymap
  59. LIGO/Virgo trigger S200115j: Possible host galaxies
  60. LIGO/Virgo S200114f: Candidates from SAGUARO observations
  61. LIGO/Virgo S200114f: No counterpart candidates in Fermi-LAT observations
  62. LIGO/Virgo S200114f: Candidates from the Zwicky Transient Facility
  63. Fermi-LAT Gamma-ray Observations of IceCube-200109A and detection of a possible new gamma-ray source, Fermi J1055.8+1034
  64. LIGO/Virgo 200112r: No counterpart candidates in Fermi-LAT observations
  65. IceCube-200109A: IceCube observation of a high-energy neutrino candidate event
  66. IceCube-200107A: IceCube observation of a high-energy neutrino candidate event
  67. LIGO/Virgo 200105ae: No counterpart candidates in Fermi-LAT observations
  68. LIGO/Virgo S200105ae: A subthreshold GW compact binary merger candidate
  69. IceCube-191231A: IceCube observation of a high-energy neutrino candidate event
  70. LIGO/Virgo S191216ap: Two candidate counterparts from UKIRT/WFCAM z-band observations
  71. LIGO/Virgo S191213g: Pan-STARRS monitoring shows PS19hgw (AT2019wxt) to be fading quickly
  72. LIGO/Virgo S191222n: No counterpart candidates in Fermi-LAT observations
  73. GRB 191220A: SAO RAS possible OT detection
  74. LIGO/Virgo S191216ap: Subaru/Hyper Suprime-Cam observations of GW+IceCube+HAWC error region
  75. LIGO/Virgo S191213g: VLT spectrum of AT2019wxt (PS19hgw) - a probable Ib supernova
  76. LIGO/Virgo G191216ap: No counterpart candidates in Fermi-LAT observations
  77. LIGO/Virgo S191215w: No counterpart candidates in Fermi-LAT observations
  78. IceCube-191215A - IceCube observation of a high-energy neutrino candidate event
  79. LIGO/Virgo S191213g: No counterpart candidates in Fermi-LAT observations
  80. Possible HAWC-detected GRB 191210A: Fermi-LAT Upper Limits
  81. Possible HAWC-detected GRB 191210A: no neutrino counterpart candidate in ANTARES search
  82. Possible HAWC-detected GRB 191210A: Swift-XRT observations
  83. GRB 191207A: Possible GRB detected in Fermi-LAT blind search
  84. LIGO/Virgo S191205ah: GMG detection of SAGUARO transient
  85. LIGO/Virgo S191205ah: No counterpart candidates in Fermi-LAT observations
  86. LIGO/Virgo S191204r: No counterpart candidates in Fermi-LAT observations
  87. IceCube-191204A - IceCube observation of a high-energy neutrino candidate event
  88. LIGO/Virgo S191129u: No counterpart candidates in Fermi-LAT observations
  89. IceCube-191122A - IceCube observation of a high-energy neutrino candidate event
  90. IceCube-191119A - IceCube observation of a high-energy neutrino candidate event
  91. Announcing the GW Treasure Map
  92. LIGO/Virgo S191110af: Potential pulsar counterparts
  93. LIGO/Virgo S191110af: No counterpart candidates in Fermi-LAT observations
  94. LIGO/Virgo S191109d: No counterpart candidates in Fermi-LAT observations
  95. LIGO/Virgo S191105e: No counterpart candidates in Fermi-LAT observations
  96. Konus-Wind observation of GRB 191031D: correction to GCN 26126
  97. Possible GRB 191025A: FRAM-Auger optical limit
  98. Swift Trigger 931384: possible GRB 191025A
  99. GRB 191024A: Afterglow Upper Limits with LCO
  100. GRB 19011A: Optical Afterglow Detection with LCO

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